1. Field Of The Invention
This invention relates to a continuous miner, and more particularly, to a continuous miner that includes a dust scrubber system for dust control having ductwork in the duct system that increases in capacity during operation of the scrubber system.
2. Description Of The Prior Art
In underground mining, it is well known to provide a continuous mining machine which includes a material dislodging mechanism positioned on the front end of the mining machine for dislodging material from a mine face. The dislodged material is conveyed rearwardly of the mining machine by a conveying means positioned on the continuous mining machine. The continuous mining machine is designed to continuously advance and dislodge material being mined to form an entry or tunnel in the material seam.
Various types of continuous mining machines having different types of duct assemblies are known.
U.S. Pat. No. 3,712,678 discloses a continuous miner which is provided with a dust collecting means comprising ductwork adapted to receive dust entrained air adjacent to and rearwardly of the material dislodging device and mobile frame carried ductwork operable to alternatively discharge the exhaust air to opposite sides of the machine. U.S. Pat. No. 3,792,568 discloses a continuous mining machine with an air scrubber including a duct located adjacent the mine face for removing the dust laden air at the mine face, a scrubber mechanism operatively connected to the duct for separating the dust from the air moving through the duct, and a second duct operatively connected to the scrubber mechanism for directing the resultant clean air back toward the mine face.
U.S. Pat. No. 3,810,677 discloses a mining machine having a boom enclosed dust collector assembly for use in a coal mining operation wherein the dust-laden air from a mining machine is gathered directly from said operation, collected in the mining machine boom and selectively wetted and separated by centrifugal processing into a coal slurry for disposal and clean air for exhaust.
U.S. Pat. No. 4,076,315 discloses a dust collecting device including an intake means for delivering air to a rotating fan where the dust-laden air is wetted and an outlet means directing air and slurry from the fan and into a curtain to an area of dust concentration.
U.S. Pat. No. 4,157,204 discloses a coal mine ventilation system which ensures proper ventilation near the working area of a mining machine. The mining machine has mounted on it a panel on a movable frame, a conventional line curtain fixed to the mine floor and roof and located adjacent to the panel and a fluid spray system to direct a flow of air across the mine face and into the curtain.
U.S. Pat. No. 4,249,778 discloses a mining machine with an air-cleaning system comprising ducting for conducting dust-laden air, a scrubber for applying liquid to the dust-laden air, and a demister for thereafter removing moisture from the air. The outlet of the demister is higher than the inlet opening to create a dead air space which aids in preventing the reentrainment of moisture in the exhaust air.
U.S. Pat. No. 4,380,353 discloses a dust control system for a mining machine for controlling respirable dust in coal mining operations, compriisng a ductwork system having intakes adjacent to the cutter head of the mining machine, a fan for drawing air through the ductwork system, a flooded bed scrubber in the ductwork system upstream from the fan for suspending the dust particles in solution and a demister with a sump system for directing the dust-laden water to a point adjacent the material dislodging mechanism. Also disclosed is a hinged and telescoping duct system associated with the dust control system.
U.S. Pat. No. 4,463,973 discloses a dust collecting device for use in mining machines which is connected to a suction source and which opens near the cutting area of a mining machine. The dust collecting device has two duct sections movable relative to each other. One duct section is mounted on the cutter boom of the mining machine and has an extendable upper wall, connected through a hinged plate, that abuts a wall of the first duct section which is mounted on the mining machine body. A lower hinge plate connected to the bottom wall of the duct swivels freely and rests on the bottom wall of the first duct to enclose the space between the two duct sections.
U.S. Pat. No. 4,531,784 discloses a continuous mining machine having a dust collector including a housing having a plurality of laterally spaced inlets for receiving dust-laden air, and a duct system connecting the inlets to corresponding outlets where the air with substantially all of the dust removed therefrom is discharged. A plurality of water spray manifolds are positioned in the housing at the inlets and direct a high pressure liquid spray toward the outlets to induce an accelerated flow of dust-laden air into the dust collector.
U.S. Pat. No. 4,557,524 discloses a mining machine having a dust collection system mounted on the boom and mobile frame of the mining machine with a transition section connecting the intake on the boom and the fixed duct section on the mobile frame. The transition section consists of a two piece arrangement wherein each piece is hinged to the intake duct section and is capable of slidingly engaging the end of the fixed duct section adjacent the boom to connect and seal the intake duct section to the fixed duct section as the boom pivots upwardly and downwardly.
U.S. Pat. No. 4,840,432 discloses a self-propelled continuous mining machine with a dust collecting system positioned on the mobile frame assembly for inducing a flow of air through a hollow interior portion of the boom assembly connected by an arcuate pivot joint to the dust collecting system on the mobile frame.
Although the prior art continuous mining machines include various types of ductwork systems, it does not disclose an increasable capacity ductwork system and there is a need for an improved mining machine having an increasable capacity ductwork system such as a channel system with a movable top or a rigid lower structure with a flexible top which can inflate or expand to increase the cross section of the scrubber ducts while mining, yet retaining a lower collapsed height for tramming purposes.